Source: Dragon #305
You have learned to strike when your opponent is most vulnerable - at the same instant he or she strikes at you.
Prerequisite: Dex 13+, Dodge, Weapon Finesse, base attack +1 or higher.
Benefit: If the opponent you have designated as your Dodge target (see the Dodge feat) misses you with a melee attack or melee touch attack and you are wielding a weapon you have chosen for the Weapon Finesse feat, you may attempt an attack of opportunity against that opponent.
This feat can be used only once per round, even if you are allowed more than one attack of opportunity each round.
Special: A fighter may select Agile Riposte as one of his fighter bonus feats.
Note: This feat appeared first in d20 Modern. This version, slightly modified from the original, is a variant suggested for use with D&D.